Method of producing color photographic images by development



Patented Aug. 7, 1934 PATT OFFECE METHOD OF PRODUCING COLOR PHOTO- GRAPHIC IMAGES BY DEVELOPMENT Merrill W. Seymour, Irondequoit, N. Y., ,assignor to Eastman Kodak Company, Rochester, N. Y., a corporation of New York No Drawing. Application May 11, 1931 Serial No. 536,659

6 Claims.

This invention relates to photographic developers capable of producing directly colored images.

Developers have been known which are capable of developing silver halide salts directly to colored compounds by means of a combination between an oxidation product of the developer and another substance added to the developer, or by the oxidation of the developer itself by the silver halide to a colored substance.

I have found a class of organic substances very useful in processes of this sort. These substances are completed or partial condensation products of a hydrazine with an acyl acetic acid ester. The pyrazolones are examples of these products which are particularly useful. These substances are made by condensing the corresponding hydrazines with [i keto-acid esters, such as acetoacetic ethyl ester, or with ,8 aldehyde acids.

In carrying out these condensations a hydrazine may be used to react with, for example, formyl acetic acid esters, aceto acetic acid esters, or benzoyl acetic acid esters. Intermediate products, particularly the a'ryl hydrazones of these acyl acetic acid esters, are usefulin place of the pyrazolones.

Pyrazolones 'that I have found particularly useful are the following: 1-phenyl-3-methyl-5- pyrazolone, l-p-nitrophenyl-3-methyl-5pyrazolone, 1-a-naphthyl-3methyl-5-pyrazolone, l-pbromophenyl 3 methyl-5-pyrazolone, pyrazolone (unsubstituted), B-phenyl-pyrazolone.

These substances and any others which I may use are distinguished from other pyrazolones previously mentioned as follows. They are all characterized by the fact that at. the 4 position there is always an active methylene group. This statement is made clearer by consideration of the following formula, which is general for the substances under consideration.

H H CY a is CAN aryl group or an alkyl group. Preferably not both X and Y are hydrogen. It is seen that the 4 position is occupied by the methylene (CH2) group. This is the particular characteristic of all of the compounds which I use.

An example of the use of an intermediate is p-nitro-phenyl-hydrazone of aceto-acetic ethyl ester, an intermediate product in the formation of 1p-nitro-phenyl-3-methyl-5-pyrazolone.

The pyrazolones and hydrazones described react in the developer with the oxidation products of p-phenylene diamine or its allqrl substituted compounds such as p-amino-diethylaniline or p-amino-dimethylaniline to form insoluble dyes. Although the p-phenylene diamine may be, and is preferably alkyl substituted, one of the amino groups must be unsubstituted. The other may have one or two alkyl substituents.

' An example of the use of the invention follows. The following developer is made up:

EXAMPLE I Solution A 1-pheny1-3-methyl-5-pyrazolone; Acetone 0.5 grams 10. cc.

Solution B For use add Solution A to Solution B.

The exposedplate or film is developed in this developer, which gives a certain amount of re- 8 duced silver image, together with an image of a complex compound having a red or rose color. The silver is removed by means of well-known bleaching solutions such as Farmer's reducer or a bleach consisting of potassium ferricyanide and potassium bromide. The Farmers reducer is preferably used-as two separate solutions, one containing the potassium ferricyanide and the other the hypo. With the ferricyanide-bromide type of bleach it is necessary to follow the treatment with fixing in hypo to remove soluble silver salts.

It is, of course, requisite that the bleach used should not affect the colored image. This-requirement will exclude the use of certain types to a color separation image.

2 of bleaching solutions though a number are available and useful.

Another example of a suitable developer is the following:

" EXAMPLE II p-nitroyhenyl hydrazone of acetoacetic.

ethyl ester 0.5 gm. Sodium carbonate, 10% solution '75. cc. p-amino dimethyl aniline hydrochloride 0.1 gm. Acetone 40. cc. Water to 200. cc.

As before, the film is developed in this developer and the silver is bleached out with one of the solutions mentioned. This yields an image of a peculiar shade of rose color.

A third suitable developer is EXAMPLE III Sodium carbonate 10% aqueous solu- Water to 100. cc.

The components of a developer of the type I have described may be combined as illustrated in the foregoing examples and applied as a complete color developing solution to an exposed.

silver halide layer, or one of the essential components which react to form the colored substance may be incorporated into a photographic emulsion, as by adsorption to the silver halide grains, and the other components, including preferably, the reducing agent, may be applied in solution after exposure.

As an example of the use of these color forming substances adsorbed to silver halide salts, I may make an emulsion of silver bromide containing a condensation product of a hydrazine with an acylacetic acid ester. Particularly useful products of this kind are the pyrazolones. Such an emulsion is coated on a suitable support, dried, and exposed in the usual manner, as for example, It is then developed in a p-phenylene-diamine as described and the coupling action of the oxidation product of the developer -with the pyrazolone or hydrazone takes place in the presence of the image which is being developed in exactly the same way as previously described. I

In mentioning processes of this kind, it is understood that I do not limit myself to cases in which the color former is truly adsorbed, as I contemplate the use of such color formers in any process where they are adsorbed, absorbed, or merely occur in close association with the sensitive salts. v

It has previously been suggested to use a pyrazolone in a photographic developer-in place of reducing agents such as methyl paramino phenol sulphate (Elon). It is to be noted that I do not use the pyrazolones I have mentioned in this way, but onlyas substances which may couple with another substance on development to form a colored substance. This forms the basis of a quite different process.

What I claim is:

1. A photographic developer containing a condensation product of phenyl hydrazine with an acyl acetic acid ester, the condensation product being selected from the group consisting of a pyrazolone having an active methylene group in the 4 position and the hydraz'one of the acyl acetic acid ester, the developer containing also a substance which on development reacts with said condensation product to produce a colored image.

2. A photographic developer containing pphenylene diamine and a pyrazolone having an active methylene group in the 4 position.

3. A photographic developer containing a pyrazolone having an active methylene group. in the 4 position and a substance which on development reacts with said pyrazolone to pro- ,duce a colored image.

4. A photographic developer containing pphenylene' diamine and a condensation product of phenyl hydrazine with an acyl acetic acid ester, the condensation product being selected from the group consisting of a pyrazolone having an active methylene group in the 4 position and the hydrazone of the acyl acetic acid ester.

5. A photographic developer containing. pphenylene diamine and a hydrazone of an acyl acetic acid ester.

6. A photographic developer containing a hydrazone of an acyl acetic acid ester and a substance which on development reacts with said hydrazone to produce a colored image.

MERRILL W. SEYMOUR. 

